Construction monitoring of cut and cover tunnels Available to Purchase

Over 700 instruments were installed to monitor the performance of the cut and cover tunnels that carry the Channel Tunnel Rail Link through Ashford. Careful monitoring confirmed design assumptions and provided a sound basis for changes to the construction sequence that accelerated the works. This paper highlights key features of the monitoring system. It describes the instruments that were installed, reviews their performance, and identifies practical issues that were addressed during the contract. The results help to quantify toe movements of embedded retaining walls. They identify variations in temporary prop loads that are explained by reference to the method of excavation and changes in prop stiffness during initial loading. Prompt reporting and open access to the monitoring data developed confidence and trust between the project partners, and led to closer interaction and greater efficiency.